1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to an active matrix type liquid crystal display device which can reduce holding capacity for holding lighting of pixels for a given time and feeding resistance thereof thus enhancing numerical aperture.
2. Description of the Related Art
An active matrix type liquid crystal display device generally adopts a system in which liquid crystal is sandwiched between a pair of substrates which face each other in an opposed manner and pixels are selected by pixel electrodes which are driven by a large number of switching elements represented by thin film transistors formed on one of the above-mentioned pair of substrates. One type of the liquid crystal display device adopting such a system is a so-called vertical field type in which on the other substrate (second substrate) which faces one substrate (first substrate) of the above-mentioned pair of substrates, color filters and common electrodes are formed or the color filters are also formed on the first substrate.
As another system, there exists a so-called IPS system in which counter electrodes which correspond to the common electrodes are formed on the above-mentioned first substrate side. Also with respect to this system, there has been known a system which forms color filters on either the first substrate side or the second substrate side.
The vertical field type liquid crystal display device includes a plurality of gate lines which extend in the first direction (usually horizontal scanning direction) and are arranged parallel to each other and a plurality of drain lines which extend in the second direction which crosses the gate lines (usually vertical scanning direction) and are arranged parallel to each other. The liquid crystal display device further includes switching elements such as thin film transistors or the like in the vicinity of respective crossing portions of the gate lines and drain lines and pixel electrodes which are driven by the switching elements.
In this vertical field type liquid crystal display device, the common electrodes are formed on the second substrate such that the common electrodes face the pixel electrodes in an opposed manner, an electric field is generated between the common electrodes and the selected pixel electrodes in the direction which approximately crosses a surface of the substrate at a right angle, and lighting of the pixels is performed by changing the orientation of liquid crystal molecules sandwiched between the pixel electrode and the common electrodes.
On the other hand, in the IPS type liquid crystal display device, gate lines, drain lines, and switching elements similar to those of the vertical field type liquid crystal display device are formed on an inner surface of the above-mentioned first substrate, comb-shaped pixel electrodes are formed on the same substrate, and counter electrodes are formed close to the pixel electrodes on the same substrate. Then, an electric field is generated between the selected pixel electrodes and the counter electrodes in the direction approximately parallel to a surface of the substrate, and lighting of the pixels is performed by changing the orientation direction of liquid crystal molecules arranged between the pixel electrodes and the counter electrodes. As a liquid crystal display device which has developed this type, there exists a liquid crystal display device which adopts a matted electrode as the counter electrodes and forms comb-shaped pixel electrodes as a layer above or below the counter electrodes.
In both of the above-mentioned type liquid crystal display devices, the charge storing capacity for holding the lighting time of the pixels which are lit due to selection at a given value (hereinafter, simply referred to as “holding capacity”) is formed in regions where the pixel electrodes and the gate lines are overlapped or regions where other electrode lines which are formed such that the other electrode lines transverse the pixel electrode forming region and the pixel electrodes, and feeding paths for storing charge in the holding capacity is formed of either the gate lines or the above-mentioned electrode lines.